Despite the poor thermal performance of draperies hung on traverse rods they are the most popular window treatment, accounting for over 60% of all sales. The yearly expenditure for draperies approaches two billion dollars. Fabrics draped at windows have a long historical precedent and are popular because of the wide variety in appearance and price. However, the thermal performance of a drapery hung on a traverse rod is poor. Studies have shown the increased effectiveness over a single glazed double hung window to be a low 10%. This is primarily due to the rod design which positions the drapery fabric at an excessive distance from the window, leaving the top and bottom edges unsealed. Convective heat flow if exaggerated and causes what is known as the `tunnel` effect where heated air is continually drawn past the window surface and cooled. In typical residential construction the heat source is located under the window, aggravating this problem. In the worst instance the drapery fabric is hung to the floor, often completely covering the heat source and trapping the heated air.
Previous attempts have been made to correct this heat loss by providing an insulating liner in conjunction with the drapery or by forming the draperies themselves from an insulatingtype material. The Lindenmayer U.S. Pat. No. 3,372,729 discloses draperies having insulation properties designed to be hung on a conventional rod at some distance from a window. The Ratliff U.S. Pat. No. 3,001,578 discloses a conventional pinch pleat drapery which includes magnetic means for sealing the draperies together at the bottom center edges. The patents to Hopper U.S. Pat. No. 4,039,019 and Boyle U.S. Pat. No. 4,188,991 disclose draperies or drapery liners including a reflective window-facing layer. However, none of these references, nor any other patents or references known to this inventor, has solved the problem of the heat loss caused by the unsealed drapery or liner positioned several inches from the window or door.